Sanctuary in Goa is a maritime state along the central west coast of Indian peninsula. The Western Ghats of India is one of the 34 biodiversity hotspots in the world (Myer et al. 2000). Goa (3702km2) occupies about 2% area of Western Ghats (Joshi & Janarthanam 2004) and its biodiversity is under threat due to deforestation (Myer 1990; Menon & Bawa 1997; Jha et al. 2000). Reptilian fauna is largely dominated by the Indo-Chinese element, relicts India’s geological history.
Approximately, out of 530 species of reptiles presently reported from India 197 comprises endemics, of these 98 endemics out of 260 species are reported from the Western Ghats (Daniel 2002). In spite of this high endemism, herpetofauna in India has received poor attention and has not been studied in detail (Vasudevan et al. 2001) and it is possible that a few of them have already been lost even before being reported (Dar et al. 2008). Pit vipers belong to the family Viperidae and subfamily Crotalinae, which is represented by 21 genera. Nineteen species of pit vipers have been reported from India (Bhide 2001) including seven from the Western Ghats (Kumar et al. 1998). All these species barring Trimerusurus gramineus are endemic to Western Ghats (Whitaker 1969; Whitaker & Captain 2004; Khaire 2006). Information on the distribution, abundance and present conservation status of pit vipers in Western Ghats is scanty.
The present study was conducted in Mhadei Wildlife Sanctuary (MWS: 208.48km2), Bhagwan Mahaveer Wildlife Sanctuary and National Park (BMWS & NP: 241km2), Bondla Wildlife Sanctuary (BWS: 8km2), Netravali Wildlife Sanctuary (NWS: 211.05km2), Cotigao Wildlife Sanctuary (CWS: 86km2) and in cashew Anacardium occidentale plantations within and adjoining areas of these protected areas (PA). Altitude of the study areas ranged from 20 to 800 m and consists of west coast tropical evergreen, cane brakes, wet bamboo brakes, west coast semi-evergreen, moist bamboo brakes, lateritic semi-evergreen forest, slightly moist teak forest, southern moist deciduous forest, southern secondary moist mixed deciduous forest, south Indian subtropical hill savannah woodland and southern subtropical hill forest.
The ambient temperature usually fluctuates between 15 and 30 0C. The distribution and abundance of pit vipers was studied in all the PAs mentioned above using band transect following Dahanukar & Padhey (2005). Surveys were carried out on foot in different seasons (summer - March to May, monsoon - June to October and winter - November to February) during June 2005 to January 2009. Surveys were conducted during both day and night in predetermined paths or roads (2500x20 m). Geographical position of each study area and location of each observation of the snake was recorded using a hand-held geographical positioning system (GPS). Relative humidity and ambient temperatures of the observation sites were recorded using a hygrometer and mercury thermometer respectively.
Bondla Wildlife Sanctuary
Netravali Wildlife SanctuaryCotigao Wildlife Sanctuary
Cotigao Wildlife Sanctuary
In all, 45 transects were sampled to assess the species distribution and abundance of pit vipers. Three species of pit vipers, T. gramineus, T. malabaricus and H. hypnale were recorded during this study. A total of 356 pit vipers were observed during this study. H. hypnale was the most abundant species contributing (46.63%, n = 166) followed by T. gramineus (28.09 %, n = 100) and T. malabaricus (25.28%, n = 90). The abundance of pit vipers varied in different study locations.
All three species of pit vipers were observed in all the study locations, except the BWS, where only T. gramineus was found. However, the locals report the presence of T. malabaricus in BWS. The forests type preferred by each species of pit vipers. The temperature and humidity of the area during the present study ranged from 20.88 ± 5.25 0C to 32.44 ± 0.88 0C and 53 ± 4% to 93 ± 2% respectively.